1. Field of the Invention
The invention relates to communications and, in particular, to providing an indication to a user of the capabilities of a communication network for handling special number calls, such as 9-1-1 calls, prior to the user placing a special number call over the communication network.
2. Statement of the Problem
In the United States, basic 9-1-1 service and Enhanced 9-1-1 service (E9-1-1) were developed for landline-based telephony as emergency reporting services where a calling party can dial 9-1-1 in emergency situations. When a 9-1-1 call is placed, the call is answered at a Public Safety Answering Point (PSAP, also known as a “Public Safety Access Point”). An operator at the PSAP converses with the calling party to determine information on the emergency situation. For instance, the operator may ask the calling party for his/her name, the nature of the emergency, the location of the emergency, etc. Based on the gathered information, the operator contacts emergency personnel to respond to the emergency. E9-1-1 has the additional features of automatically providing the operator with some information on the calling party. For instance, E9-1-1 service includes the features of Automatic Number Identification (ANI) and Automatic Location Identification (ALI). With ANI, the operator at the PSAP is automatically provided with the telephone number of the phone placing the 9-1-1 call to allow for call back. With ALI, the PSAP queries an ALI database for information on the physical location of the calling party's phone. An ALI database stores records of telephone numbers with each record containing information on a physical location (such as a street address) corresponding with a telephone number or another key. Responsive to a query from the PSAP, the ALI database returns the location information for the calling party. With the telephone number and the location information, the operator can more effectively handle the 9-1-1 call. Other countries have emergency services similar to this.
E9-1-1 service is more easily implemented for landline phones where a location of a phone is fixed. Mobile devices, such as cell phones, PCS phones, VoIP phones, etc., present another problem. The locations of mobile devices are not fixed by definition, which makes determining their location more of a challenge as compared to landline phones. Regulatory bodies, such as the Federal Communications Commission (FCC) in the United States, have set forth regulations that carrier networks, such as cellular networks, must be able to determine the location of mobile devices for 9-1-1 calls. If a mobile device is GPS enabled, then the device can provide its location to the carrier network. If the mobile device is not GPS enabled, then the carrier network has the duty to determine the location of the mobile device. A wireless carrier network, such as a cellular or PCS network, can estimate the location of a mobile device based on the location of the cell presently providing service to the mobile device, such as through a cell identifier (cell ID). The wireless carrier network may also use triangulation among multiple cells, time of arrival (TOA) information indicating the time it takes for a wireless signal from a mobile device to reach a base station, and other data to more accurately determine the location of the mobile device. The location of the mobile device may then be used to select the appropriate PSAP to handle a 9-1-1 call, and to provide the location of the mobile device to the PSAP.
Mobile VoIP also presents a problem of determining the location of the calling party. Some VoIP service providers have a VoIP user predefine a location, such as his/her home address, when the VoIP user signs up for service. If the VoIP user uses their VoIP phone away from their home address, then the VoIP service provider may require that the VoIP user enter their present address when registering with the VoIP network.
FIG. 1 illustrates a communication network 100 for providing 9-1-1 service in the prior art. Communication network 100 includes a wireless carrier network 110, an emergency services network 120, and a positioning server 132. Wireless carrier network 110 includes a base station 112 and a Mobile Switching Center (MSC) 114 that provide telephone service to a mobile phone 116. Positioning server 132 determines the location of mobile phone 116, and determines where to route 9-1-1 calls based on the location of mobile phone 116. Positioning server 132 may include the functionality of a Location Information Services (LIS) server, a Position Determining Entity (PDE) server, and/or a Serving Mobile Location Center (SMLC) server. Emergency services network 120 includes a selective router 122, a PSAP 124, and an ALI database 126.
The following illustrates a typical 9-1-1 call in communication network 100. Assume that a user of mobile phone 116 places a 9-1-1 call. Base station 112 receives the call, and transmits the call to MSC 114. MSC 114 identifies the call as a 9-1-1 call, and transmits an indication of the 9-1-1 call to positioning server 132. Responsive to the indication of the 9-1-1 call, positioning server 132 determines the location of mobile phone 116. Based on the location of mobile phone 116, positioning server 132 generates routing information for the call in order to route the call to a PSAP responsible for mobile phone 116. The routing information typically includes an Emergency Service Number (ESN) that represents an emergency service zone corresponding with the location of mobile phone 116, an Emergency Service Routing Key (ESRK), and other information. Positioning server 132 then transmits the routing information to MSC 114, which routes the 9-1-1 call to selective router 122 based on the routing information.
Selective router 122 queries a selective router database (not shown) to select the appropriate PSAP 124 to handle the call based on the ESN. Selective router 122 then routes the call to PSAP 124. PSAP 124 receives the call that includes the call back number (ANI) of mobile phone 116 and receives the ESRK. PSAP 124 then queries ALI database 126 based on the ESRK of mobile phone 116 to obtain the present location of mobile phone 116. ALI database 126 communicates with positioning server 132 to obtain the location associated with the ESRK of mobile phone 116. ALI database 126 then provides the location of mobile phone 116 to PSAP 124, and an operator at PSAP 124 handles the 9-1-1 call.
One problem with present communication networks is that a user may be in an area where the 9-1-1 capabilities of the network are poor, and the user may not know that the 9-1-1 capabilities are poor. In one example, a mobile user may travel to an area where a wireless carrier network is not able to accurately determine the location of the mobile user. As a consequence of not being able to accurately determine the location, the wireless carrier network may not be able to determine where to route a 9-1-1 call. Even if the call is routed correctly, a PSAP serving the 9-1-1 call may not receive accurate location information from the ALI database and may have a hard time determining the actual location of the mobile user.
In another example, VoIP service providers sometimes struggle with how to determine the location of VoIP users. Certain areas of VoIP networks are not presently configured to determine the location of a VoIP phone in the event of a 9-1-1 call. Unfortunately, the VoIP user may not have an idea that they are in an area where the VoIP network can only provide limited 9-1-1 capabilities or no 9-1-1 capabilities at all. Similar problems exist for other special number calls or abbreviated dialing calls, such as 1-1-2 calls in Europe.